my 9 month old female pug seems to be having a problem with her rt. rear leg she limps on occasion and sometimes drags the leg, she hops when she runs and seems to favor this leg. this all started bout 1 month ago, at first i just thought that my 10 month old male had hurt her , but now i'm just not sure. she has vet appt. to be checked.she'll often lay on her stomach and with her hind legs straight back and when in this position and i call her she will drag back end for few seconds, i would like to know what is causing this to happen.